This invention relates to an organic electroluminescent (hereinafter referred to as "EL") device, and more particularly to an organic EL device used for a plane light source, a plane display device or the like and a method for manufacturing the same.
In manufacturing of an organic EL device which has been conventionally executed, a light-permeable indium-tin oxide (ITO) film is first formed all over a front surface of a glass substrate in a vacuum atmosphere. Then, the ITO film is formed into a stripe-like shape by etching, resulting in a plurality of transparent electrodes or first electrodes being provided which are arranged in juxtaposition to each other while being spaced from each other at predetermined intervals. Then, the transparent electrodes are formed thereon with a hole transport layer, which is made of a hole transport material such as a triphenylamine derivative (TPD) or the like by vacuum deposition. Subsequently, a layer made of an electron transport material such as an aluminum quinolinol complex (Alq.sub.3) acting as a luminous material is laminated on the hole transport layer, resulting in a luminous material layer being formed by vacuum deposition. Then, Al, Li, Ag, Mg, In or the like is deposited in a stripe-like manner on the luminous material layer so as to extend in a direction perpendicular to a pattern of the transparent electrodes, to thereby provide a plurality of rear electrodes or second electrodes. Such construction permits portions of the luminous material layer positioned at intersections between the transparent electrodes and the rear electrodes to define luminous sections, resulting in forming a dot matrix. In operation of the organic EL device thus constructed, a current is flowed to the luminous sections positioned on the intersections between the transparent electrodes acting as anodes and the rear electrodes acting as cathodes, leading to luminescence of the luminous sections.
In order to carry out either fine display or display on a large image plane by means of such a dot matrix, it is required to increase the number of dots. This requires to reduce a thickness of the transparent electrodes and increase a length thereof, leading to an increase in resistance of the transparent electrodes. Such an increase in resistance causes the transparent electrodes to be varied in resistance, to thereby cause a current flowed to the luminous sections to be varied, resulting in luminance or brightness of display on the image plane being rendered nonuniform.
Also, in simple matrix driving wherein the luminous sections are subsequently scanned for luminescence, lines from the transparent electrodes and rear electrodes are subsequently selected one by one to carry out luminescence of each of the luminous sections. This causes a period of time for which a current is flowed to each one of the transparent electrodes to be proportional to an inverse of the number of transparent electrodes. Thus, an increase in number of transparent electrodes causes luminous time of the luminous sections to be reduced correspondingly. Also, an increase in number of dots for the purpose of increasing definition of the image plane causes the transparent electrodes and rear electrodes to be reduced in width, to thereby render connection of external wirings to the transparent and rear electrodes highly troublesome and difficult.